A tethered-balloon PTRMS sampling approach for surveying of landscape-scale biogenic VOC fluxes

Landscape-scale fluxes of biogenic gases were surveyed by deploying a 100 m Teflon tube attached to a tethered balloon as a sampling inlet for a fast-response proton-transfer-reaction mass spectrometer (PTRMS). Along with meteorological instruments deployed on the tethered balloon and a 3 m tripod and outputs from a regional weather model, these observations were used to estimate landscape-scale biogenic volatile organic compound fluxes with two micrometeorological techniques: mixed layer vari- ance and surface layer gradients. This highly mobile sam- pling system was deployed at four field sites near Barcelona to estimate landscape-scale biogenic volatile organic com- pound (BVOC) emission factors in a relatively short period (3 weeks). The two micrometeorological techniques were compared with emissions predicted with a biogenic emission model us- ing site-specific emission factors and land-cover character- istics for all four sites. The methods agreed within the un- certainty of the techniques in most cases, even though the locations had considerable heterogeneity in species distri- bution and complex terrain. Considering the wide range in reported BVOC emission factors for individual vegetation species (more than an order of magnitude), this temporally short and inexpensive flux estimation technique may be use- ful for constraining BVOC emission factors used as model inputs.